Woods, C. L., Hunt, S. L., Morris, D. M. & Gordon, A. M. 2012: Epiphytes influence the transformation of nitrogen in coniferous forest canopies. Boreal Env. Res. 17: 411–424.
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Malmaeus, J. M., Rydin, E., Jonsson, P., Lindgren, D. & Karlsson, O. M. 2012: Estimating the amount of mobile phosphorus in Baltic coastal soft sediments of central Sweden. Boreal Env. Res. 17: 425–436.
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Tuovinen, N., Weckström, K. & Salonen, V.-P. 2012: Impact of mine drainage on diatom communities of Orijärvi and Määrjärvi, lakes in SW Finland. Boreal Env. Res. 17: 437–446.
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Kjellsson, J. & Döös, K. 2012: Surface drifters and model trajectories in the Baltic Sea. Boreal Env. Res. 17: 447–459.
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Kõrs, A., Vilbaste, S., Käiro, K., Pall, P., Piirsoo, K., Truu, J. & Viik, M. 2012: Temporal changes in the composition of macrophyte communities and environmental factors governing the distribution of aquatic plants in an unregulated lowland river (Emajõgi, Estonia). Boreal Env. Res. 17: 460–472.
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Hosia, A., Granhag, L., Katajisto, T. & Lehtiniemi, M. 2012: Experimental feeding rates of gelatinous predators Aurelia aurita and Mnemiopsis leidyi at low northern Baltic Sea salinity. Boreal Env. Res. 17: 473–483.
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Blyth, E., Clark, D. B., Ellis, R. & George, C. 2012: Using earth observation data to evaluate a land surface model in three Siberian catchments. Boreal Env. Res. 17: 484–494.
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Woods, C. L., Hunt, S. L., Morris, D. M. & Gordon, A. M. 2012: Epiphytes influence the transformation of nitrogen in coniferous forest canopies. Boreal Env. Res. 17: 411–424.

The transformation of atmospherically-deposited nitrogen (N) by coniferous forest canopies has primarily been attributed to epiphytic lichens, despite microbes being present on leaf surfaces. We examined the relative contribution of live foliage with its epiphytic microbes and epiphytic lichen on N transformations in black spruce canopies. The epiphytic microbes and live foliage intercepted 27% of rainwater, 72% of incident nitrite + nitrate, and 63% of incident ammonium, while enriching throughfall with organic N by 52%. Epiphytic lichens on dead lower branches intercepted 60% of rainwater and depleted absolute amounts of inorganic and organic N, even though solute concentration increased as water passed through the lichens. Relationships were found between the number of colony forming units of epiphytic fungi and the depletion and enrichment of different forms of N in throughfall. Intensive forest management practices could result in the canopy being a net sink for N as a result of higher lichen biomass.

Malmaeus, J. M., Rydin, E., Jonsson, P., Lindgren, D. & Karlsson, O. M. 2012: Estimating the amount of mobile phosphorus in Baltic coastal soft sediments of central Sweden. Boreal Env. Res. 17: 425–436.

A new dataset based on 102 sediment cores was examined to estimate the amount of phosphorus (P) that will eventually be released to the water column from the Baltic coastal sediments along the Swedish coast between Öregrund and Oxelösund. Total P (P_tot) concentration in the surface sediments varied between 840 and 7100 µg g^–1 dry weight (dw) with an average of 1650 µg g^–1 dw. In deep sediments, the P_tot concentration was around 1000 µg g^–1 with small variation. The difference between surface concentration and the stable, deeper, concentration represents P to be released, i.e. the mobile P. Pools of mobile P varied between 1.5 and 18.2 g m^–2. Correlations between surface P_tot concentrations and amounts of mobile P were strong (r² = 0.88). We estimate the amount of mobile P in the coastal sediments of the investigated region to be between 1000 and 4000 tonnes. Assuming a turnover time of the mobile P between three and ten years gives an average annual P release of 100–1300 tonnes yr^–1.

Tuovinen, N., Weckström, K. & Salonen, V.-P. 2012: Impact of mine drainage on diatom communities of Orijärvi and Määrjärvi, lakes in SW Finland. Boreal Env. Res. 17: 437–446.

The top/bottom paleolimnological approach was used to assess (1) the spatial extent of the effect of acid mine-drainage from the Orijärvi mine tailings on diatom communities of Orijärvi and Määrjärvi, and (2) the change that occurred in these communities as compared with the pre-disturbance conditions. Altogether eight cores were retrieved from the lakes and examined for their diatom remains. The compositional change in the diatom communities was assessed by detrended correspondence analysis and changes in their diversity by the Shannon diversity index (H'). The metal pollution affected diatoms at community levels resulting in a shift in dominant taxa and an overall decrease in diversity (both lakes), and at the individual level causing alteration in valve morphology (Orijärvi). The proportion of benthic and tychoplanktonic diatoms increased while planktonic diatoms markedly decreased in abundance. This study demonstrates that the used approach is a useful tool in larger-scale assessments of recent change and ecological reference conditions of surface waters.

Kjellsson, J. & Döös, K. 2012: Surface drifters and model trajectories in the Baltic Sea. Boreal Env. Res. 17: 447–459.

Results from recent deployments of surface drifters in the Baltic Sea are presented. For the first time ever, the realism of model-generated trajectories was assessed by a statistical comparison with trajectories of SVP drifters. The absolute dispersion (i.e. the distance from the initial point as a function of time) was found to be somewhat underestimated by the model trajectories. A severe underestimation of the relative dispersion (pair separation) was also noted, which may, to some extent, be due to the limited resolution of the model. However, the relative dispersion was also found to be very dependent on the initial separation of the model trajectory pairs. After filtering the inertial oscillations, a good agreement of the velocity auto-correlations between the drifters and model trajectories was found. A discussion on the impact of these results on future trajectory modelling in the Baltic Sea is also provided.

Kõrs, A., Vilbaste, S., Käiro, K., Pall, P., Piirsoo, K., Truu, J. & Viik, M. 2012: Temporal changes in the composition of macrophyte communities and environmental factors governing the distribution of aquatic plants in an unregulated lowland river (Emajõgi, Estonia). Boreal Env. Res. 17: 460–472.

The species composition and dominating species were determined in five 25-m river reaches every week or every second week during the vegetation period of three consecutive years (2006–2008). The number of species and the composition of macrophytes at each site differed from year to year. A total of 33 taxa of vascular plants were identified. Butomus umbellatus, Glyceria maxima, and Sagittaria sagittifolia were registered at all sites each year. The number of constant species was low and we identified a large number of occasional taxa. The dominant species varied during the vegetation period. According to CCA, year was a statistically important parameter for determining the composition of the macrophyte community. The hydrological parameters (discharge, water level, water temperature) had an effect on the distribution of the aquatic plants. Among hydrochemical parameters conductivity, O₂, O₂ saturation, and sulphate content were statistically significant parameters governing the distribution of the macrophyte taxa.

Hosia, A., Granhag, L., Katajisto, T. & Lehtiniemi, M. 2012: Experimental feeding rates of gelatinous predators Aurelia aurita and Mnemiopsis leidyi at low northern Baltic Sea salinity. Boreal Env. Res. 17: 473–483.

The effect of the northern Baltic Sea's low salinity on feeding rates of a native scyphozoan Aurelia aurita and a recent invader to southern Baltic Sea, ctenophore Mnemiopsis leidyi, was investigated experimentally. Incubations with Acartia spp. prey (4.19–25.16 indiv. l^–1) were used to estimate clearance rates for both predators. Mnemiopsis leidyi digestion times were measured for several natural prey items. Wet weight (ww):length/diameter relationships as well as clearance rates (0.49 ± 0.15 l g_ww^–1 h^–1 [mean ± SE] for M. leidyi [mean oral–aboral length ± SD = 9.6 ± 1.5 mm]; and 0.18 ? 0.07 l g_ww^–1 h^–1 [mean ± SE] for A. aurita [mean bell diameter ± SD = 37.3 ± 6.9 mm]) and digestion times at salinity 5.7 were within the ranges reported from higher salinities. These preliminary results suggest that the low salinity does not significantly depress the feeding rates or potential predatory impact of these gelatinous predators.

Blyth, E., Clark, D. B., Ellis, R. & George, C. 2012: Using earth observation data to evaluate a land surface model in three Siberian catchments. Boreal Env. Res. 17: 484–494.

In this paper, we analyse the ability of the JULES (Joint UK Land Environment Simulator) model to simulate the physical conditions in the terrestrial Arctic using satellite-based earth observation data products. Catchment-average seasonal surface temperatures and snow cover are constructed over the largest river basins of the Eurasian Arctic (the Ob, Lena and Yenisei) and compared with the modelled values. The results indicate that the modelled snow cover decreases too quickly in spring in all studied areas, and that the modelled surface temperature of snow-free areas is too high. There are several causes of uncertainty in both the model outputs and the earth observation products, and care has to be taken to ensure consistent use and sampling of the data. The results indicate that earth observation products provide important information that can assist in the diagnosis of problems in a land-surface model.